In a bid to extend the patent on its OxyContin painkiller by six months, Purdue Pharma is running clinical trials on more than 150 children between the ages 6 and 16 years old who have “moderate to severe” pain and would require opioid analgesics, according to reports. If the results pass muster with the FDA, the drugmaker can ring the register for another six months beyond April 2013, when the OxyContin patent expires.